مرکز منطقه ای اطلاع رساني علوم و فناوري

Abstract :

Impedance matching networks couple a generator to a load. When lossless matching elements are used, the load power $P$ and the power $P\´$ extracted from the generator terminals are the same. Then the familiar conjugate impedance match condition maximizes $P\´$ , and hence $P$ . But if the matching elements are lossy $P \\neq P\´$ ; the power difference $P\´ - P$ is wasted in the matching network. Maximizing $P\´$ does not maximize $P$ . Suppose the load is purely resistive and that the quality factors of all elements used in the matching network must not exceed a prescribed value $Q$ . If the load resistance value $R$ is not prescribed, but can be adjusted to facilitate matching, then the maximum obtainable load power is $P_m$ , given by Theorem 1. When $R$ is prescribed, the maximum power may be less than $P_m$ . However, there is a range of load resistance values, wide in many cases, for which Theorem 2 applies to deliver the same maximum power $P_m$ . $P_m$ depends on $Q$ and on another quality factor $q$ of the generator. $P_m$ is small if $Q \\ll q$ , as may be the case if the generator is a short receiving antenna.